JP2006156631A - Wiring board with resistive element, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable application to the inner layer of a multilayer substrate and reduction in the variation of resistance values as well as improvement in accuracy of a shape at the time of resistance body formation by improving the shape of a resistance body in a wiring board with a resistive element. <P>SOLUTION: On the substrate of a base, the wiring board with a resistive element is connected with a resistance body 7 and a pair of element electrodes via a second electrode 4 provided for mitigating contact resistance. It is provided with an element electrode 3 provided on the substrate, a second electrode provided on this element electrode, an insulating layer 5 embedded where the upper surface of the second electrode is exposed on the whole surface from the substrate between the element electrode and the second electrode, and a resistance body provided between the second electrodes. The insulating layer and the upper surface of the second electrode exposed on the insulating layer upper surface are flat. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wiring board with a resistance element optimal for miniaturization of electronic devices and high-density mounting of electronic components, a wiring board with a resistance element built in a component, and a manufacturing method thereof.

  In recent years, with the demand for smaller and thinner electronic components, electronic components and printed wiring boards (hereinafter referred to as wiring boards) on which these electronic components are mounted are also reduced in size and thickness due to finer and higher density patterns. Thinning is required by using a thin material. Along with this, a wiring board with a resistive element having a built-in component in which a resistive element formed by using a resistor chip component that has been conventionally surface-mounted as a printed resistor has been developed. As a result, the mounting area of the resistor is reduced, and the thickness of the resistor can be made thinner than that of the chip component. Therefore, the wiring board can be reduced in size and thickness.

  Regarding a conventional resistor forming method in a wiring board with a resistor element, a method of printing a resistor on a pair of element electrodes on a substrate by a screen printing method or silver as a second electrode on a copper electrode (hereinafter referred to as an element electrode) There is a method in which a resistor is printed after an electrode is printed. There is also a method in which a resistor is printed after forming a second electrode by performing nickel gold plating on a copper substrate.

  However, when the screen printing method is used for forming the resistor, it is difficult to form a fine pattern, because printability problems such as printing bleeding due to a step on the printing surface, printing sagging, and film thickness variation cannot be avoided. Furthermore, in the case of a resistor formed on a conventional element electrode, the contact resistance at the interface between the copper of the element electrode material and the resistor increases due to the influence of moisture and oxygen in the air after the resistor is formed. There was a problem that the value fluctuated. As a solution, there is a method of forming a second electrode made of a material having a small contact resistance between the element electrode and the resistor.

  When a silver electrode printed and formed with a silver paste is used for the second electrode, fluctuations in resistance can be reduced. However, as described above, printing sagging due to a step on the printing surface, film thickness variation, etc. occur, resulting in fine There is a problem that it is more difficult to form a proper interelectrode resistance. Furthermore, since it is more difficult to form a fine resistor, there is a problem in applying it to the inner layer of the multilayer substrate.

  There is also a method of forming a second electrode by performing nickel gold plating on the copper substrate, but the subsequent surface treatment is difficult, and the oxide film treatment called blackening treatment cannot be performed on the copper pattern, so the conductor pattern and resin There is a problem that it is difficult to secure the adhesiveness to the inner layer of the multilayer substrate and it is difficult to apply to the inner layer of the multilayer substrate (see Patent Document 1 and Patent Document 2).

The known literature is described below.
JP-A-1-173778 Japanese Unexamined Patent Publication No. 64-42895

  Therefore, the present invention has been made to solve these problems, and by improving the shape of the resistor, it is possible to improve the shape accuracy at the time of forming the resistor, reduce the fluctuation of the resistance value, and apply it to the inner layer of the multilayer substrate. The purpose is to make it possible.

The invention according to claim 1 of the present invention is a wiring board having a resistance element in which a resistor and a pair of element electrodes are connected via a second electrode for reducing contact resistance on a base substrate,
An element electrode provided on the substrate; a second electrode provided on the element electrode;
An insulating layer laminated on the entire surface of the substrate, wherein the element electrode and the second electrode are embedded with the upper surface of the second electrode exposed;
A resistor provided between the second electrodes;
And the upper surface of the insulating layer and the second electrode exposed on the upper surface of the insulating layer are flat.

  The invention according to claim 2 of the present invention is the wiring board with a resistance element according to claim 1, wherein the thickness of the second electrode is in the range of 10 μm to 20 μm.

  The invention according to claim 3 of the present invention is the wiring board with a resistance element according to claim 1 or 2, wherein a wiring pattern is further provided on the insulating layer.

The invention according to claim 4 of the present invention is the resistance element according to any one of claims 1 to 3, further comprising a resistance element in which the resistor and the element electrode are connected via a second electrode for reducing contact resistance. In the method for manufacturing a wiring board with a substrate, (a) a step of forming a wiring pattern and an element electrode on the substrate;
(B) forming a second electrode on the element electrode; (c) covering the wiring pattern, the element electrode and the second electrode on the substrate with an insulating resin to form an insulating layer; and (d). A resistance comprising at least a step of polishing the surface of the insulating layer until the surface of the second electrode is exposed, and (e) a step of forming a resistor between the second electrodes exposed on the insulating layer. It is a manufacturing method of a wiring board with an element.

  The invention according to claim 5 of the present invention is the method of manufacturing a wiring board with a resistance element according to claim 4, further comprising a step of providing a second wiring pattern on the insulating layer.

  The invention according to claim 6 of the present invention is the method for manufacturing a wiring board with a resistance element according to claim 4 or 5, wherein the second electrode is formed by screen printing a conductive paste. is there.

  The invention according to claim 7 of the present invention is characterized in that the resistor is formed by screen printing a resistor paste in which a conductive filler is dispersed in a resin binder. It is a manufacturing method of the wiring board with a resistance element of 1 item | term.

  According to the present invention, when the second electrode and the printed resistor are formed of the polymer paste material, the resistor forming portion is flat, so that the printing sagging due to a step with the electrode is prevented and the printed resistor is formed in a good shape. Can do. Furthermore, since the resistor is connected to the element electrode via the silver electrode, it is possible to form a more reliable polymer resistor element with suppressed fluctuations in resistance value, and the wiring board with the resistor element can be applied to the inner layer.

  By the above manufacturing method, a fine resistor shape can be formed satisfactorily, and the accuracy at the time of element formation can be improved. Further, by adopting a structure in which the resistance element is connected to the element electrode via the silver electrode of the second electrode, it is possible to reduce the contact resistance and reduce the resistance value fluctuation. Furthermore, since the wiring board manufactured by the above manufacturing method can be subjected to subsequent surface treatment, such as blackening treatment, it can be applied to the inner layer of the multilayer substrate.

  A wiring board with a resistance element and a method for manufacturing the same according to the present invention will be described below based on an embodiment.

  In FIG. 1, a pair of element electrodes 3 and a first wiring pattern 2 are formed on a base substrate 1 and are provided on a pair of element electrodes 3 via a second electrode 4 formed of a conductive resin. In the structure for forming the resistor 7, the insulating resin 5 is formed on the entire surface from the base substrate 1 to the device electrode 3 and the second electrode 4 until the upper surface of the second electrode 4 is exposed and exposed. This is a wiring board with a resistance element in which a resistor 7 is formed on the upper surface of the second electrode 4. The first wiring pattern 2 has a function of a wiring circuit portion and a terminal portion that inputs and outputs to the outside (not shown).

  The manufacturing method of the wiring board with a resistance element of the present invention shown in FIG. 1 will be described. A step of printing and forming the second electrode 4 on an arbitrary element electrode 3 provided on the base substrate with a conductive resin such as a conductive paste; and the upper surfaces of the base substrate, the element electrode, and the second electrode, A step of covering the surface of the wiring board with the insulating resin 5, a step of scraping and planarizing the surface of the insulating resin 5 by physical polishing or chemical treatment until the second electrode 4 is exposed, and a resistor forming portion. And a step of printing a resistor resin 7 such as a resistance paste, and a method of manufacturing a wiring board with a resistance element manufactured by the method. The manufacturing method of the present invention is characterized in that before the resistor is formed, the upper surface of the insulating resin and the upper surface of the second electrode are flattened on the same surface, and the resistor is formed on the flat surface.

  In FIG. 2, a pair of element electrodes 3 and a first wiring pattern 2 are formed on a base substrate 1 and are provided on a pair of element electrodes 3 via a second electrode 4 formed of a conductive resin. In the structure for forming the resistor 7, the insulating resin is used until the upper surface of the second electrode 4 is exposed on the entire surface from the base substrate 1 to the device electrode 3, the first wiring pattern 2, and the second electrode 4. 5, a resistor 7 is formed on the exposed upper surface of the second electrode 4, and a second wiring pattern 6 is formed on the upper surface of the insulating resin 5. The first and second wiring patterns 2 and 6 have a function of a wiring circuit unit, and the first wiring pattern and the second wiring pattern 6 are conductive holes formed in an insulating resin (via holes are plated in via holes). A wiring circuit is formed via (not shown).

  A method for manufacturing the wiring board with a resistance element shown in FIG. 2 will be described. A step of printing and forming the second electrode 4 on an arbitrary element electrode 3 provided on the base substrate with a conductive resin such as a conductive paste; and the upper surfaces of the base substrate, the element electrode, and the second electrode, A step of covering the surface of the wiring board with the insulating resin 5, a step of scraping and flattening the surface of the insulating resin 5 by physical polishing or chemical treatment until the upper surface of the second electrode 4 is exposed, and resistor formation A method for manufacturing a wiring board with a resistance element manufactured by forming a resistor 7 by printing a resistor resin such as a resistance paste on a portion thereof. 2, the second wiring pattern 6 is formed on the upper surface of the insulating resin 5, and the first wiring pattern and the second wiring pattern 6 have via plating conduction holes formed in the insulating resin. A wiring circuit is formed through this, and since a known manufacturing method is used in the formation, description thereof is omitted. Therefore, the manufacturing method of the wiring board with a resistance element shown in FIG. 2 can be applied to the inner layer of the multilayer board. The manufacturing method of the present invention is characterized in that before the resistor is formed, the upper surface of the insulating resin and the upper surface of the second electrode are flattened on the same surface, and the resistor is formed on the flat surface.

The conductive resin described in the present invention is a paste-like conductive resin in which a conductive filler is blended based on a resin. The resin used is phenol, epoxy, urethane, acrylic or the like, and gold, silver, nickel, carbon or the like is used for the conductive filler. Due to its workability, a one-pack type thermosetting conductive resin to which a curing agent is added is easy to use. The conductive resin used here is a paste material intended to reduce contact resistance and obtain resistance value stability by interposing between a resistor and a copper foil electrode. For example, a resin using silver particles as a filler A silver paste dispersed in a binder is a material having electrical properties of about 10 ⁻⁵ Ω · cm. Specific examples include polymer type silver paste LS-504J manufactured by Asahi Chemical Research Laboratory.

  The resistor material described in the present invention is a material in which carbon particles are used as a main conductive filler and dispersed in a binder such as a phenol resin, an epoxy resin, a xylene resin, a polyimide resin, or a diallyl phthalate resin. Specific examples include carbon resistance paste TU-500-8 manufactured by Asahi Chemical Research Laboratory.

  More specifically, the manufacturing method of the wiring board with a resistance element described above will be described with reference to FIGS. 3 (a) to 3 (e) and FIGS. 4 (g) to 4 (k). 3 (a) to 3 (f) and FIGS. 4 (g) to (k) are manufacturing process diagrams showing a manufacturing process of a wiring board with a resistance element.

  First, as shown in FIG. 3A, the copper foil on the base substrate 1 is patterned by a photo process method, and a wiring substrate having the first wiring pattern 2 and the pair of element electrodes 3 is manufactured. Next, as shown in FIG. 3B, a conductive resin is screen-printed on an arbitrary element electrode 3 to form the second electrode 4. As the conductive resin, for example, there is a silver paste dispersed in a resin binder using silver particles as a filler. Next, as shown in FIG. 3C, the entire surface of the substrate 1 on which the second electrode 4 is formed is covered with an insulating resin 5. Next, as shown in FIG. 3D, the insulating resin 5 is shaved by physical polishing or chemical treatment to produce a planarized surface with the upper surface of the second electrode 4 exposed. As a specific method of polishing, ceramic buffing (SPC # 600) manufactured by Jaburo Industry, followed by non-woven fabric buffing (JP buffing surface UF # 800, ULF # 1200) can be used. Next, as shown in FIG. 3E, the second wiring pattern 6 is formed on the planarizing insulating resin 5 excluding the resistor forming portion by an additive method used in a normal build-up process. Next, as shown in FIG. 3F, a resistor paste is screen-printed on the resistor forming portion to form the resistor 7, and the wiring substrate 8 with a resistor element is manufactured. In some cases, the second wiring pattern 6 is not formed.

  Further, in order to apply to the component built-in board in which the wiring board 8 with the resistance element is inserted in the inner layer of the board, the following steps shown in FIGS. 4G to 4K are further performed. As shown in FIG. 4G, a surface roughening step is performed on the wiring board 8 with a resistance element. The surface roughening treatment is performed in order to strengthen the adhesion between the second wiring pattern 6 made of copper and the insulating resin to be laminated. The surface treatment step used here may be any step as long as the resistance element is resistant to the surface treatment step, and examples thereof include CZ treatment of MEC. After this surface roughening treatment step, the resin-coated copper foil 10 is laminated by vacuum pressing as shown in FIG. Specific examples of the copper foil 10 with resin used here include MR-700 manufactured by Mitsui Mining & Smelting Co., Ltd. and R-0880 manufactured by Matsushita Electric Works, Ltd. Subsequently, as shown in FIG. 4 (i), after a predetermined via hole 12 is formed by a UV-YAG laser, desmear treatment with an alkaline permanganate is performed. Thereafter, via plating 13 is performed by an electroless copper plating process and an electrolytic copper plating process as shown in FIG. Thereafter, as shown in FIG. 4 (k), a third wiring pattern 14 is produced by a subtractive method. In this way, one conductor layer is completed on the wiring board with a resistance element. Furthermore, a desired buildup layer is formed by repeating the processes after the lamination of the copper foil with resin. As a result, a wiring board with a resistance element is formed in the board to produce a component built-in board.

  Specific embodiments of the present invention will be described below with reference to FIGS. 3 (a) to 3 (e) and FIGS. 4 (g) to 4 (k).

  As a material for the base substrate 1, BT copper-clad laminate CCL-HL-830 manufactured by Mitsubishi Gas Chemical Co., Ltd. was used. First, as shown in FIG. 3A, the copper foil was patterned by a subtractive method.

  Next, as shown in FIG. 3 (b), a conductive resin was screen printed on an arbitrary element electrode 3 and thermally cured at 150 ° C. to form a second electrode 4. As the second electrode material, polymer type silver paste LS-504J manufactured by Asahi Chemical Laboratory was used.

  Next, as shown in FIG. 3C, the entire surface of the substrate 1 on which the silver electrode of the second electrode 4 was formed was covered with an insulating resin 5. The insulating material used here is ABF-GX manufactured by Ajinomoto Co. or S-flex manufactured by Sumitomo Chemical.

  Next, as shown in FIG. 3D, the insulating resin provided in the previous step was polished by buffing to produce a planarized surface exposing the second electrode. Here, first, a ceramic buff SPC # 600 manufactured by Jablo Industries was used for the first axis, and the thickness of the insulating resin on the silver electrode was polished and the surface step was made uniform. Finish polishing was performed using JP buff surface UF # 800, which is a non-woven buff made by Jablo Industry, on the second axis, and ULF # 1200 on the third axis.

  Next, as shown in FIG. 3E, the copper foil of the second wiring pattern 6 is formed on the planarized surface of the insulating resin 5 excluding the resistor forming portion by an additive method used in a normal build-up process. did.

  Next, as shown in FIG. 3 (f), a resistor paste was screen-printed on the resistor forming portion to form the resistor 7, and a wiring board with a resistor element was manufactured. As a resistance paste, a carbon resistance paste TU-500-8 manufactured by Asahi Chemical Research Laboratories was used for thermosetting at 200 ° C. to prepare a resistor 7. As a result, it was possible to suppress the printing sagging when the resistor 7 was formed, and to improve the accuracy when the element was formed.

Further, in order to apply the wiring board with a resistance element to a component-embedded board inserted in the inner layer of the board, the following steps of FIGS. As shown in FIG. 4G, after the resistor 7 is formed, CZ treatment of MEC Co., Ltd. is applied as a surface roughening step, and after this surface roughening treatment 9 step, Mitsui as shown in FIG. MR-700 (Cu: 12, Resin: 50) of copper foil with resin 10 manufactured by Metal Mining Co., Ltd. was laminated by heating and pressurizing at a pressure of 40 kg / cm ² and a temperature of 170 ° C. for 2 hours using a vacuum press.

  Subsequently, as shown in FIG. 4 (i), a predetermined via hole 12 was formed by a UV-YAG laser, and then desmear treatment with an alkaline permanganate was performed.

  After that, as shown in FIG. 4 (j), 0.3 μm plating is performed by the electroless copper plating process of Rohm and Haas Electronic Materials Co., Ltd., and then via plating 13 having a thickness of 10 μm is performed by electrolytic copper plating, and conduction between layers is performed. I took.

  Thereafter, as shown in FIG. 4 (k), a third wiring pattern 14 was produced by a subtractive method. In this way, the resistor element was placed in the substrate to produce a component built-in substrate.

It is a partial expanded side sectional view of an example of a wiring board with a resistance element of the present invention. It is a partial expanded side sectional view of an example of a wiring board with a resistance element of the present invention. (A)-(e) is a sectional side view which shows the manufacturing process of the wiring board with a resistive element which concerns on this invention. (G)-(k) is a sectional side view which shows the manufacturing process of the wiring board with a resistive element which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... (Base) board | substrate 2 ... 1st wiring pattern 3 ... Element electrode 4 ... 2nd electrode (silver electrode)
DESCRIPTION OF SYMBOLS 5 ... Insulating resin 6 ... 2nd wiring pattern 7 ... Resistance body 8 ... Wiring board 9 with a resistance element ... Surface roughening process 10 ... Copper foil 11 with resin 11 ... UV-YAG laser 12 ... Via hole 13 ... Via plating 14 ... First 3 wiring pattern

Claims (7)

A wiring board having a resistance element in which a resistor and a pair of element electrodes are connected via a second electrode for reducing contact resistance on a base substrate,
An element electrode provided on the substrate; a second electrode provided on the element electrode;
An insulating layer laminated on the entire surface of the substrate, wherein the element electrode and the second electrode are embedded with the upper surface of the second electrode exposed;
A resistor provided between the second electrodes;
And the upper surface of the insulating layer and the second electrode exposed on the upper surface of the insulating layer are flat.   The wiring board with a resistance element according to claim 1, wherein the thickness of the second electrode is in the range of 10 μm to 20 μm.   The wiring board with a resistance element according to claim 1, wherein a wiring pattern is further provided on the insulating layer. 4. The method of manufacturing a wiring board with a resistance element according to claim 1, further comprising a resistance element in which the resistor and the element electrode are connected via a second electrode for reducing contact resistance. 5.
(A) forming a wiring pattern and device electrodes on the substrate;
(B) forming a second electrode on the device electrode;
(C) covering the wiring pattern, the element electrode and the second electrode on the substrate with an insulating resin to form an insulating layer;
(D) polishing the surface of the insulating layer until the surface of the second electrode is exposed;
(E) forming a resistor between the second electrodes exposed on the insulating layer;
A method of manufacturing a wiring board with a resistance element, comprising:   5. The method of manufacturing a wiring board with a resistance element according to claim 4, further comprising a step of providing a second wiring pattern on the insulating layer.   6. The method of manufacturing a wiring board with a resistance element according to claim 4, wherein the second electrode is formed by screen printing a conductive paste.   The said resistor is formed by screen-printing the resistance paste which disperse | distributed the conductive filler in the resin binder, The manufacturing of the wiring board with a resistive element of any one of Claim 4 thru | or 6 characterized by the above-mentioned. Method.

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